Supersensitizing combinations comprising simple cyanine dyes and metal salts



Dec. 1o, 1957 i E. JONES SUPERSENSITIZING COMBINATIONS 'COMPRISING SIMPLE CYANINE DYES AND METAL SALTS Filed March 8, 1955 Fig. 2

|||I lll'l Il i CADMIUM CHLOE/0E ./EA/v E. JONES A l JIWENToR.

United States Patent O SUPERSENSITIZING COMBINATIONS COMPRIS- gli? EIMPLE CYANINE DYES AND METAL Jean E. Jones, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application March S, 1955, Serial No. 492,950

16 Claims. (Cl. 96-104) This invention relates to photographic emulsions containing simple cyanine dyes, and in supersensitizing cornbination therewith, certain metal salts.

It is known in the art of making photographic emulsions that certain dyes of the cyanine class alter the sensitivity of photographic emulsions of the gelatino-silverhalide kind, when the dyes are incorporatedin the emulsions. It is also known that the sensitization produced by a given dye varies somewhat with the type of emulsion in which the dye is incorporated. Furthermore, the sensitization of a given emulsion by a given dye may be altered by varying the conditions in the emulsion. For example, the sensitization may be increased by increasing the silver ion concentration or decreasing the hydrogen ion concentration (i. e., increasing the alkalinity) or both. Thus, sensitization can be increased by bathing plates, coated with a spectrally sensitized emulsion, in

water or in aqueous solutions of ammonia. Such a process of altering the sensitivity of a sensitized emulsionl by increasing the silver ion concentration and/or by decreasing the hydrogen ion concentration is commonly called hypersensitization Hypersensitized emulsions have generally poor keeping qualities.

l have now found a new means of altering the sensitivity in emulsions containing cyanine dyes. Since the conditions in the emulsion, i. e., the hydrogen ion and/ or the `silver ion concentration undergo no significant change in my method, I shall designate my new method as a kind of supersensitization.

it is, therefore, an object of my invention to provide.

photographic emulsions containing cyanine dyes, and in supersensitizing combination therewith, certain metal salts. Another object is to provide a process for preparing these supersensitized emulsions. Other objects will become apparent from a consideration of the following description and examples.

The simple cyanine dyes useful in practicing my invention can advantageously be represented by the following general formula:

I. Z Z1 `o=cH-o('='oH-oH).. -R1

wherein R and R1 each represents an alkyl group, such as methyl, ethyl, n-propyl, carbethoxymethyl, benzyl, etc. (e. g., an alkyl group containing from 1 to 2 carbon atoms, etc.), m and n each represents a positive integer of from l to 2, X represents an acid radical, such as chloride, iodide, bromide, perchlorate, p-toluene-sulfonate, benzenesulfonate, ethylsulfate, methylsulfate, etc., and Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, e. g., a heterocyclic nucleus of the thiazole series (e. g., thiazole, 4-methylthiazole, 4-phenylthiazole, S-methylthiazole, 5-pheny1- thiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole, etc.), a heterocyclic nucleus of the benzothiazole series Patented Dec. 10, 1957 (e. g., benzothiazole, 4chlorobenzothiazole, 5-chlorobenzothiazole, 6-chlorobenzothiazole, 7-ch1orobenzothiazole, 4 methylbenzothiazole, 5 methylbenzothiazole, 6methylbenzothiazole, 5-bromobenzothiazole, 6-bromobenzothiazole, 4 phenylbenzothiazole, 5 phenylbenzothiazole, 4 methoxybenzothiazole, 5 methoxybenzothiazole, 6 rnethoxybenzothiazole, 6 iodobenzothiazole, S-iodobenzothiazole, 4-ethoxybenzothiazo1e, 5- ethoxybenzothiazole, 5,-dimethoxybenzothiazole, 5-hydroxybenzothiazole, 6-hydroxybenzothiazole, etc.), a heterocyclic nucleus of the naphthothiazole series (e. g., a-naphthothiazole, -naphthothiazole, 7-methoxy-a-naphthothiazole, 8-methoxy-a-naphthothiazole, S-methoXy-- naphthothiazole, S-ethoXy-a-naphthothiazole, etc.), a heterocyclic nucleus of the benzoselenazole series (e. g., benzoselenazole, S-chlorobenzoselenazole, 6-methoxybenzoselenazole, S-methoxybenzoselenazole, etc.), a heterocyclic nucleus of the naphthoselenazole series (e. g., wnaphthoselenazole, It-naphthoselenazole, etc.), a heterocyclic nucleus of the oxazole series (e. g., 4-methyloX- azole, S-methyloxazole, 4-phenyloxazole, 4,5-diphenyloxazole, 4-ethyloxazole, 4,5-dimethyloxazole, S-phenyloxazole, etc.), a heterocyclic nucleus of the benzoxazole series (e. g., benzoxazole, 5-hydroxybenzoxazole, 6hydroxy benzoxazole, 5-ch1orobenzoxazole, S-methoxybenzoxazole, 6-methoxybenzoxazole, S-phenylbenzoxazole, 5- bromobenzoxazole, etc.), a heterocyclic nucleus of the naphthoxazole series (e. g., a-naphthoxazole, IB-naphthoxazole, etc.), a heterocyclic nucleus of the Z-quinoline series (e. g., Z-quinoline, 6-methyl2quinoline, 7-methy1- Z-quinoline, S-methyl-Z-quinoline, 6-chloro-2-quinoline, 8- chloro-Z-quinoline, 4chloro2quinoline, 5-ethoxy-2-quinoline, S-ethoxy-Z-quinoline, 7-ethoXy-2-quinoline, 6-hydroXy-Z-quinoline, 7-hydroxy-2-quinoline, 6-meth0Xy-2- quinoline, etc.), a heterocyclic nucleus of the 4quinoline series (e. g., 4quinoline, 6-methoXy-4-quinoline, 7-methyl-t-quinoline, 8-methyl-4-quinoline, etc.), etc.

The metal `salts which can be used in practicing my invention advantageously include those represented by the following general formula:

wherein M is a cadmium or zinc atom and X1 is a chlorine or bromine atom. Cadmium chloride has been found to be particularly useful in practicing my invention, although other water-soluble salts wherein X1 represents an anion other than bromide or chloride (e. g., sulfate, nitrate, iodide, acetate, etc.) can also be used in my invention (though not as advantageously, in general).

My invention is directed to the supersensitization of washed photographic silver chloride or silver chlorobromide emulsions.

According to my invention, I incorporate one or more of the cyanine dyes selected from those represented by Formula l above with one or more of the metal salts selected from those represented by Formula II in a washed photographic silver chloride or silver chlorobromide emulsion. My supersensitizing combinations can be employed in photographic emulsions where the carrier is gelatin, or where the carrier is other than gelatin, e. g., a resinous substance or cellulosic material which has no deteriorating eifect on the light-sensitive materials.

The sensitizing dyes and metal salts can be employed in various concentrations depending upon the eiects desired. As is well known in the art, the sensitivity conferred upon an emulsion by a sensitizing dye does not increase proportionately to the concentration' of the dye in the emulsion, but rather passes through a maximum as the concentration is increased. In practicing my invention, the sensitizing dyes of Formula I are advantageously employed at or near their optimum concentration.

The opti-mum concentration of an individual sensitizing dye can be determined in a. manner Well known to those skilled in the art by measuring the sensitivity of a series of test portions of the same emulsion, each portion conemulsion containing a combination of the aforesaid sensitizingy dyes and metal salts whereby a supersensitizing effect isy obtained.

The metal salts of Formula II are useful not only taining a different concentrationA of the sensitizing dye. in their supersensitizing effect, but in that they exhibit Ordinarily, the optimum or near optimum concentrations an eect in stabilizing the emulsions against fog. This orf' the c yanine dyes selected from those represented by concomitant effect is illustrated below. Formula I above, which I employ in practicing myinven- The. following examples will serve to illustrate further tion, are of the order of from 0'-.l to 0.3 g. per moi. of the manner of practicing my invention. silver halide in the emulsion. In Table I below, to different portions of the same The metal salts selected from those represented by batch of washed photographic' gelati-nofsilver-chlorobro- Formula PI above can advantageously be employed in mide emulsion were addedV (1i). acyanine dye selected concentra-tionsy on the ordery of' from 5 to 3'5 g. per mol. from those of Formula I and (2) a combina-tion ofthe of silver" halide in the emulsion'. cyanine dye of Formula I- and cadmium chloride in the Generally speaking, the. ratio of concentration of the amounts shown in the table. Before coating, the emulcyanine dye of' Formula I to the metal salt of Formula sions were digestedl fora short time in a tank maintained H' canvaryratherfwidely in my combinations, e. g., from at 52 C. The different portions of emulsion were then lrllU to 11200 by: weight in many cases. coated on4 supports and exposed in the usual manner in a The methods of incorporating sensitizing dyes and spectrograph and ay sensitometer (type Ib) through either met'alsalts in emulsions are' well known to those skilled 20 a Wratten No. l2 iilter, i. e., a ilter which transmits subiir the art- The meta-l salts can be directly dispersed in stantiall-yno light, of wavelength shorter than about 495 the emulsions or theycan be dissolvedv in water and added mu (except for about 1% between 300 and 340 mu), or inthe form of their aqueous solutions. While the sensia Wratten No. 47 l'ter, i. e., a l'ter which transmits tizifn'gi dyes can be directly dispersed in the emulsions, it only light bet'vreenV about 355 mu and 53-5 mu; and the is convenient to addthe dyes in the form of solutions exposed emulsions developed in the usual manner. The inappropriate solvents. Methanol, ethanol, pyridine, etc. speed (minus blue and blue, respectively), gamma and have'v proveny satisfactory for many ofthe dyes of Formula fog for cach of the coatings was then determined. The Il. Acetone has also been found to be a suitable solvent results are recorded in Table I.

Table P l0 S d CdGlz, /1 pee Example Dye (gJmol. AgX) gJmol. Gamma Fog AgX Minus Blue Blue {(a) 1',3diethyl-6'-methoxy--phonylthiaf. 3.2 v .04 1 2-cyanine-p-toluenesulfonate (0.20)

(b) dye (a) (0.20) 2. 8 .04 (c) 1,3 diethyl 6' -vmethoxythia 2 eya- 3.0 .04 2 nine iodide (0.20).

(d) dye (c) (0.20) 5. 6 .04 (e) 3,3-diethyl-4,5,4,5dibenzothiacyanine 2.46 .04 3'. iodide (0.20). A

(f) dye (e) (0.20) 2. 48 .04 (g) 1 ethyl 3 methylthla 2 cyanine-v 3. 58 .04 4 iodide (0.20).

(h) dye (g) (0.20) 3. 04- .04 (i) 1,3diethyl4-phenyloxazolo2=cyanine 4.30- g .04 5 iodide (0.20).

(j) dye (i) (0.20 3.60 .04 (k) 1,3diethy -6' -methyl4,5-benzothia 3.78 .05 6 2cyanine iodide (0.20).

(l) dye (k) (0.20) 3. 52. .05

incertain cases.` Mixtures of solvents, e. g., pyridine diluted with. methanol; or acetone, can also be used. The dyes oFonmula I and themetal salts of Formula II are dispersed.; in thetnished, washed emulsions and should be uniformlydistributed? throughout the emulsions. The following procedure is satisfactory: Stock solutions of the sensitizing: dyes andi metal salts desired are prepared `by dissolvingathesameiin-appropriate solvents as described abover. 'Ehem to the: owable gelatine-silver-chloride or silver-chlorobrornide-l emulsion, the desired amounts of the; stock: solution( o one of the dyes (or metal salts) Varevslowly added', while stirringv ther emulsion. Stirringfis ycontinuedluntilf the; dye is thoroughly incorporated in the emulsion'.` Then thedesired amount of the stock solution of the metalY salt (or dye, if metal salt has been added first) is slowly added to the emulsion, while stirring. Stir-ringl is continued` until the second solutionv is thoroughly incorporated. The supersensitized emulsion can then be. coated out ont a suitable support, such as glass, cellulose derivativeiilm,-resiniilrrnorl paper, to a suitable thicknessjand; allowedr to. dry. The.` detailsof such, coating methodoare welll knownto.- those skilled in the art. The foregoing, procedures and proportions. are torbe.; regarded only as illustrative; Clearly, my invention is directed to any. Washed. silver chloride: or silver. chlorobromide In Table' II below, to different portions of the same batch` of washed, gelatinoesilver-chlorobrornide emulsion (coating series l) or washed, pure gelatino-silver chloride emulsion (coating series 2 and 3') were added (l) l,1Ldiethyl2,2cyanine iodide (coating series 1 and 2) or l,1"-dimethyl-2,2cyanine iodide (coating series 3), (2) cadmium chloride, and (3) a combination of 1,1- diethyl2,2'cyanine iodide or l,ldimethyl2,2cyanine iodide, and cadmium chloride, in the amounts shown in the table. The same unsensitized emulsion batch was employed in coatings 2 and 3, but a diierent batch of emulsionwasemployed in coating series 1. ln some instances, a given coating,` gavea speed and gamma toolow to measure, designated in= the table. Before coating the emulsions` were digested for a short time in a tank maintained at 52 C. The different portions of emulsion were their dividedinI halt` and coated on separate supports- The coating. obtained from one-half of the portion was exposedi in the usualmanner in. a spectrograph and a sensitometerv (type Ib). through a-l Wratten No. 47 filter andi/o1'. a' Wratten No. 5.8.lter, i. e., a filter which transmitsonly light' ofi wavelengths lyingv between` 465 and 620 11111 and the; exposed. emulsions; developed in the usual manner; speed (blue. and. green), 4gamma and fog forcach: atlie-l coatings; was,y then; measured. Tfhe sectateneo ond half of each portion of emulsion was incubated at 120 F. for one week at constant humidity and then processed in exactly the same manner as the iirst half. The results are recorded in the following table. The concomitant supersensitizing and stabilizing effects of the It has also been found that certain metal salts, in addition to those represented by Formula II above, provide a stabilizing elect when used in combination with the dyes of Formula I. However, as shown in Table IV below, these other metal salts have little or no supersensicadmium chloride are evident. tizing action. The data in Table IV were obtained in Table II Fresh Incubation-1 Week at 120 F.

Dye orion Coating (g./mol. (g./mol Blue Light Ex. Green Light Ex. Blue Light Ex. Green Light Ex.

AgX) AgX) Fog Fog Speed Gamma Speed Gamma Speed Gamma Speed Gamma (a) none l (b) 0.15 (b) none (6)--.. 0.15 (11)--.. none 2 (e) none (f). 0.24 tim 3 1121 0:24

*Too W to measure.

In Table H1 below, the coatings were made in exactly the same manner as described above with reference to Table II, except that the emulsion used was a Washed, gelatino-silver-chlorobromide emulsion in every instance and in some cases a metal salt other than cadmium chlo exactly the same manner as that described above with reference to Table III, except that speed and gamma measurements were not made for the incubated coatings. The same sensitizing dye, 1,1'diethyl2,2cyanine iodide, and emulsion type (silver chlorobromide) were employed.

ride was employed (lndlcated 1n table). The table shows The results obtained are given 1n the followlng table.

Table IV Addenda Fresh Incubation, Coating Blue Light Green Light 1 week at g./mol. Exposure Exposure 120 F., Salt AgX Fog Fog Speed Gamma Speed Gamma none 062 2. 26 05 11 Pb(NOa)z 20. 0 061 2. 8 048 90 05 05 CoClgHzO 16. 5 065 2. 46 05 .05 SrClz.6H2O 16. 5 063 2. 46 05 06 LaCl?l 16. 5 066 2. 6 05 06 CaCh-. 16. 5 .066 2. 6 .05 .O5 ZnCln 16. 5 076 2. 6 04 05 *Too small to measure.

that the anion and cation of the metal salt are important in providing the eects sought. For example, cadmium nitrate is effective in stabilizing the emulsion against fog, but poor in stabilization against loss of speed. Addition of chloride or bromide ion gives improved speed stability, as shown in the table. The emulsions were sensitized with 1,1'diethyl2,2cyanine iodide (.16 g./ mol.

In Table V below, to different portions of the same batch of washed gelatinosi1ver-ch1orobromide emulsion were added (l) l,1'diethyl2,2cyanine iodide (0.16 g./mol. silver chlorobromide), (2) a metal salt as identified in the table, and (3) a combination of 1,1'diethyl 2,2cyanine iodide (0.16 g./mol. silver chlorobromide) and a metal salt in the amount shown in the table. Ex-

AgX). The results were as follows: posures were then made at 400 mu or 575 mu in a spec Table III Addenda Fresh Incubation-1 Week at 120 F.

Coating Blue Light Ex. Green Light Ex. Blue Light Ex. Green Light Ex.

Salt g./mol Fog Fog AeX Speed Gamma Speed Gamma Speed Gamma Speed Gamma.

. 054 2.1 04 0.61 04 068 4.0 108 98 .21 069 3. 1 05 1. 2 06 090 3. 2 069 1. O2 08 12. 052 2. 4 04 076 3. 7 053 0. 36 22 19. 073 l. 5 05 126 2. 6 071 0. 54 14 13. 073 2. 9 05 1. 3 05 076 1. 5 105 3. 4 06 (j) l5. 10 3. 3 06 1. 5 06 123 3. 6 063 1. 7 07 +KBr 19.0 (g) Cd(NOs)2.4H2O 21.0 .056 3 1 .055 1.4 04 .080 4 0 .084 2.1 .05 (h) {c{(1O3)2.4HiO .078 2 S .053 0.7 06 .102 3 0 .059 0.67 .09 (i) {od(N'i5iii"I 2110 ii "if "'65 ii "it ""i -l-KBr--- 19.0

trosensitometer as described in P. S. A. Journal, vol. 16B (August 1950)., page 64, and the exposed coatings developed in the usual manner. (See also, Mees, The Theory of the Photographic Process, pagesl 847-865, revised edition, MacMillan Co., 1954.) The speed (blue and. green, and thel green/blue ratio), gamma, and fog were measured. The results are given in the following table. These data show that the salts employed do exhibit supersensitization in combination with the dyes of toluenesulfonate and curve B represents the sensitivity of the same emulsion containing both 1,3'diethy16'meth Oxy-5-phenylthia-2cyaninep-toluenesulfonate and cadmium chloride. The sensitometric data for these examples are given in Example 1 of Table I.

In Figure 2' curve C represents the sensitivity of an ordinary gelatine-silver-chlorobromide emulsion sensitized with 3,3diethyl-4,5,4',5'-dibenzothiacyanine iodide and curve D represents the sensitivity of the same emul- Formula I. l0 sion containing 3,3' diethyl-4,5,4,5dibenzothiacyanine Table V Addenda Ratio Relative Relativel Speeds, Coating Speed, Gamma Speed, Gamma 575 mu 'Fog Salt g./n1ol 4001mu 575 mu Agx 400 mu 10o 2.4 27 1.a .28. .o5 100 3.9 44 2:4 .44: .05 .v 71' 3.8 41 2&3 .66` .05 (d) gNnNomeHzO 80 3.4 29 1.9 .36 .05 (e) Ca(N03')a.4H2O 32 0 100 4.0 90 2.*7 .90 .05

The data in Table VI below were obtained in exactly 25 iodide and cadmium chloride. The sensitometric measthe same manner as described above in Tables II and urements for these emulsions are given in Example 3 of Il'f. The dye used was 1,1"diethyl2,2'cyanine iodide Table I. (0-3`g/m01'. AgX) and the silver' halide emulsion was a In Figure 3 curve E represents the sensitivity of an pure, washed gelatino-silverchloride emulsion'. The ordinary gel'atino-siiver-chlorobromide emulsion sensicoatings' in series 1 and series 2 were from different 30 t'ized with l"ethyl'3-ne'thylthi'a-2'cyanine iodide and emulsion batches, althoughV the coating'sunder each series curve F representsr the sensitivityv of the same emulsion were from the same batch. The data; as inI Table III, containing' both 1"'-ethyl-B-methyltliia-Z'-cyanine iodide ShOW that While the Chloride 01 bromide i011 d0 Provide and cadmium chloride. The sensitometric measurements some supersensitizins effect. the nature 0f the cation is for these emulsions are given in Exampks 4 of Table 1. likewise quite important FOI' example, Compare COH- 35 The emulsions prepared in accordance with my invenllg 2(11) With 2(0)- EXPOSuFeS Were made hlOUgh a' tion can be coated in the usual manner on any suitable WFHCD.- N0# 58'dte1 111 all' CaSeS- The 10H Speeds' are, support, e. g., glass, cellulose nitrate film, cellulose acetate accordingly, green-Speeds; film, polyvinylacet'al resin lm, paper or metal.

Table VI Photographic silver halide emulsions, such as those l0 listed above, containing the supersensitizing combinations Addenda Green Light Exposure of m'y invention can also contain such addenda as chem- Coating ical. sensitizers e. g., sulfur sensitizers (e. g., allyl thio- Salt sim? S10/i; Gamma Fos carbamide, thiourea, allylisothiocyanate, cystine, etc.), g pee, various gold' compounds (e. g., potassium chloraurate, m (t), 05 45 aur-ic trichloride, etc.) `(see U. S. Patents 2,540,085, .019 4,0 104 2,597,856', and 2,597,915, various palladium compounds, (-2330 w52 -g such as palladium chloride (U. S. 2,540,086, potassium (i) (s) 04 chloropalladatei (LI.` S. 2,598,079), etc., or mixtures of 1 glo (,)4'1 :g such sensitizers; antifoggants, such as ammonium chloro- 007g i so 04 50 platmatey (U.V S.` 21,566,245), ammonium chloroplatinite 18.02%* :g (1U. 2,566,263), benzotriazole, nitrobenzimidazole, 5- nitfroindaz'ole, benzidine, mercaptans, etc. (see Mees, (l). g3g (,)2'4 :g "[fhe Theory'off the.' lf'hotographic Process, Macmillan gggllgriw-- gg .gan man .64.4 Rub., page.460),.131mlirtures` thereof; hardenersgsuch as od(NO3)i.4Hi0..... 23.0' .002e 1:9 .o4 55 folmadlulYdE-KU. SA 1,763,533), ChlOFnealllm 2 +KO1 9.4 19763533), glyoxalf (.U. S.. 1,870,354), dibromacrolem ggf: ,Pggfgifjf (Q). gig (Br. 406,750), etc.;'cn1o'r couplers,l such as those de Plllloa): lg-g -0027 04 scribed in U. S. Patent 2,423,730, Spence and Carroll U'.` Si Btent No. 2,640,776, etc.; or mixtures of such *T00 smut() mmsure 60. addenda. DispersingY agents for color couplers, such as Examp1e 1 but not. measurable because of" curve shape AC= thOSGv SeffOIth in U. S. Patents 2,322,027 and 2,304,940, CH:C00 canY also be employed inthe above-described emulsions. The accompanying drawing illustratesthe'supersensitiz Other addenda*y can also be employed in the emulsions of ing effect obtained'with-threeof myfnew combinations inA my invention,vv such as the azaindenes (e. g., triazainwashed,photographic gelatino-silverchlorobromide emul- 65. denes, tetrazaindenes, pentazaindenes, etc.). See, for sions. Each figure'ofY the drawing is adiagrammatic re example, U. S. Patents 2,444,605-9, 2,449,22546, coproduction of two spectrograms. In each fgureithe pending Allen et al. U. S.- application 365,541, filed July 1, sensitivity of theemulsion containing the dye ofiFormula I 1953l (now U. S.. Patent 2,735,769, issued February 21, is represented by the solid curve, while the uppermost 1956); copendingA'llen et al. U. S. application 365,542, curve (broken line) representsthe sensitivityf conferred 70 led July l1,. 1953 (now UL S. Patent 2,713,541, issued on the ernulsionby` the combinationof thedye ofFor July 19,.1955);.copendingrCarroll et al. U. S. application mula I and cadmium chloride. 365550, filed July 1i, 1953 (now U. S. Patent 2,716,062, 1n Figure l curve A- represents the sensitivity ofk an. issued.August.23,.1955.); Birr: Zeit Wiss.fPvhot'.y Photoordinary gelatinosilver chlorobromide emulsion' sensitized4 physik; vPhot'ochen'ie, volf. 47 C1952), p'p. 2-28, etc. with l,3 diethyl-6-methoxy-5plienylthia2cyaninep 75y As shown in certain of the above tables, the chloride or bromide salts of my invention need not be added to the photographic emulsion as such, but that these salts can be formed in the emulsion in situ by adding a watersoluble cadmium or zinc salt (other than bromide or chloride) in the presence of a water-soluble chloride or bromide salt (other than cadmium or zinc). The following claims are intended to cover this obvious alternative in practicing my invention.

What I claim as my invention and desire secured by Letters Patent of the United States is:

l. A Washed photographic silver halide emulsion selected from the group consisting of Washed photographic silver chloride emulsions and washed photographic silver chlorobromide emulsions containing (l) an optical sensitizing dye selected from those represented by the following general formula:

R-N-oH=oH) .-lb=CH-oH-crn,Mis-R1 wherein R and R1 each represents an alkyl group, m` and n each represents a positive integer of from l to 2, X represents an acid radical, and Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from to 6 atoms in the heterocyclic ring, and (2) from 5 to 35 grams per mol. of silver halide of a metal salt selected from those represented by the following general formula:

wherein M represents an atom selected from the group consisting Vof a cadmium atom and a zinc atom and X1 represents an atom selected from the group consisting of a chlorine atom and a bromine atom.

2. A washed photographic silver halide emulsion selected from the group consisting of washed photographic silver chloride emulsions and washed photographic silver chlorobromide emulsions containing (1) a sensitizing dye selected from those represented by the following general formula:

wherein R and R1 each represents an alkyl group containing from l to 2 carbon atoms, X represents an acid radical, and Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the benzothiazole series, those of the naphthothiazole series, those of the oxazole series, `and those of the 2-quinoline series, and (2) from 5 to 35 grams per mol. of silver halide of cadmium chloride.

3. A washed photographic silver halide emulsion selected from the group consisting of washed photographic silver chloride emulsions and Washed photographic silver chlorobromide emulsions containing (l) a sensitizing dye selected from those represented by the following general formula:

wherein R and R1 each represents an alkyl group containing from l to 2 carbon atoms, X represents an acid radical, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the benzothiazole series, those of the naphthothiazole series, those of the oxazole series, and those of the 2-quinoline series, and Z1 represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the 2-quinoline series, and (2) from 5 to 35 grams per mol. of silver halide of cadmium chloride.

4. A washed photographic gelatino-silver-chlorobrowherein R and R1 each represents an alkyl group containing from l to 2 carbon atoms, X represents an acid radical, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the benzothiazole series, those of the naphthothiazole series, those of the oxazole series, and those of the 2-quinoline series, and Z1 represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the 2-quinoline series, and (2) from 5 to 35 grams per mol. of silver chlorobromide of cadmium chloride.

5. A washed photographic gelatino-silver-chloride emulsion containing (1) a sensitizing dye selected from those represented by the following general formula:

wherein R and R1 each represents an alkyl group containing from l to 2 carbon atoms, X represents an acid radical, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the benzothiazole series, those of the naphthothiazole-series, those of the oxazole series, and those ofthe 2-quinoline series, and Z1 represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the Z-quinoline series, and (2) from 5 to 35 grams per mol. of silver chloride of cadmium chloride.

6. A washed photographic silver-chlorobromide emulsion containing (1) a sensitizing dye selected from those represented .by the following general formula:

wherein R and R1 each represents an alkyl group containing from 1 to 2 car-bon atoms, X represents an acid radical, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzothiazole series, and Z1 represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the 2-quinoline series, and (2) from 5 to 35 grams per mol. of silver chlorobromide of cadmium chloride.

7. A washed photographic gelatine-silver-chlorobromide emulsion sensitized with a supersensitizing combination comprising 1',3-diethyl-6'-methoxy-5-phenylthia-2- cyanine-p-toluenesulfonate and from 5 to 35 grams per mol. of silver chlorobromide of cadmium chloride.

8. A Washed photographic silver-chlorobromide emulsion containing (l) a sensitizing dye selected from those represented by the following general formula:

wherein R and R1 each represents an alkyl group containing from l to 2 carbon atoms, X represents an acid radical, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series, and Z1 represents the non-metallic atoms necessary to cornplete a heterocyclic nucleus of the 2quinoline series, and (2) from 5 to 35 grams per mol. of silver chlorobromide of cadmium chloride.

9. A washed photographic gelatino-silver-chlorobromide emulsion sensitized with a supersensitizing combination comprising l',3diethyl-6methyl4,S-benzothia-Z- cyanine iodide and from 5 to 35 grams per mol. of silver chlorobromide of cadmium chloride.

10. A washed photographic silver-chlorobromide emull 1 sion containing .(1)1 a sensitizing dyeselected from those represented by the following `general formula:

wherein R and R1. each representsan alkyl group containing from 1 to 2 carbon atoms, X represents an acid radical, Z represents the non-metallic atoms necessary to complete a heteroeyclic nucleusyof the oxa-zole series, and Z1 represents the non-metallicatoms necessary to complete a lieterocyclic nucleus of the 2`-quinoline series, and (2) from 5 to 35 grams per mol. of silver chlorobromide of cadmium chloride.

1l'. A washed photographic gelatino-silver-chl'orebromide emulsion sensitized with a supersersitizing combination comprising v1,3-diethyl-4-phenyloXazolo-Z-cyanine iodide and from 5 to 35 grams per m'ol. of silver chlorobromide of cadmium chloride. x l

12. A washed photographic silver-chlorobromide emulsion containing (l) a sensitizing dye selected from those represented by the following generalv formula:

lTT-Ri X wherein R and R1 each represents an alkyl group containing from 1 to 2 carbon atoms, `X represents an acid radical, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series, and Z1 represents the non-metallic atoms necessary to complete a hcterocyclic nucleus of the naphthothiazole series, and (2) from 5 to 35 `grams per mol. of silver chlorobromide of cadmium chloride.

13. A washed, photographic gelatino-silver-chlorobrowherein R a-ndpR1 each represents an alkyl group containing from 1 to 2 carbon atoms, represents an acid radical, Z represents the non-metallic `atonisv necessary to complete a heterocyclic nucleus of the 2quinoline series, and Z1 represents the non-metallic atoms necessaryto complete a hetercyclic nucleus f the 2qulir`ie series, and (2) fro'rn 5 to 35 grams permol. of silver chloride of cadmium chloride. l I i 15, A washed, photogrpiie gegfinesnver-nl-oride emulsion sensitized with Aal superseiisitizing combination comprising l,1-diethyll`2,2"cyanie iodide and from 5 to 35 grains per mol. of silver chloride of cadmium chloride. lr6. A washed photographic silver' halide emulsion selected from the group consisting of washed photographic silver chloride emulsions and washedlphotographic silver chlorobromide emulsions containing (1') an optical s'ensitizing dye selected from those represented by the follwing general formula:

wherein R and R1 each represents an allylg'ioup, a'd nv eacli-repeselfs a positiv'i'feg'eof ffor l f6 2, X r'elsents an acid radical, ardZ arid-Z1' eaclepresetsthe nohmetallic atoms necessaryv to complete a' hetero'cyclic nucleus containing from 5 to 6 atoms in they lieterocyclic ring, and (2) from 5 to 35 grams per mol. f silver halide of a water-soluble salt of avmefl selected from the group consisting of cadmium and zinc.

ieferences Cited' in the file of this patent UNITED STATES" PATENTS' 21,234,877 Martinez -Judea, 1942 213993083' Waller A'rl 213; 19.46 2.4329865-- Dm'sdaie/e't el; Dee. 16, 19147 2.5171511 Christsn.- Aug'- 81 1.9.5,0 25983079 staurfefef ar. 2.7, 1952 2,618,556 Hewnson et al Nov. 18; 1952 OTHER- RBFERNCES The Photographic Journal, January 1928, pages 21 

16. A WASHED PHOTOGRAPHIC SILVER HALIDE EMULSION SELECTED FROM THE GROUP CONSISTING OF WASHED PHOTGRAPHIC SILVER CHLORIDE EMULSIONS AND WASHED PHOTOGRAPHIC SILVER CHLOROBROMIDE EMULSIONS CONTAINING (1) AN APTICAL SENSI- 